The field of the invention relates generally to a valve assembly for one-way flow. In particular, the field of the invention relates to a modular valve assembly for sealing engagement in the neck of a flexible container, forming a closure that is airtight, shockproof, leakproof and evaporation proof. This closure is effective against leakage of fluids due to vibration as well as changes in temperature and pressure, for preventing any backflow or reentry of contaminants through the valve assembly, including air, or evaporation of fluid from the container. Moreover, if the fluid initially is sterile, the shockproof closure maintains the sterility of the remaining fluid in the container during and between dispensings of the fluid.
In dispensing sterile fluids from a container wherein the container has an extended period of use-life, it is important to prevent any back flow of contaminants into the container during and after the dispensing operation has been carried out. Contaminants in the form of materials originating from outside of the valve assembly and container may include microorganisms, atmospheric gases, moisture, dust or the like. If the sterile fluid is contaminated it can affect the quality, concentration of constituents, potency and even safety of the product. In many cases, it is highly desirable to prevent leakage and evaporation of the contents of the container between uses. At best, leakage will cause sanitary problems as well as the loss of some or the entire product. At worst, evaporation of a volatile solvent will alter the concentration of the remaining solute. This could prove dangerous.
If a container of a sterile fluid has a one-time use and the user does not intend to dispense fluid over an extended period, the problem of contaminants flowing backward into the container usually does not exist. In one known liquid handling container disclosed in U.S. Pat. No. 2,715,980 to Frick, the valve mechanism involves a valve body with a central port extending through the valve body and with branch ports extending from the central port to the outside surface of the valve body. An expansible sleeve, such as a sleeve of a rubber-like material, encloses the outside surface of the valve body preventing flow from the branch ports. When a fluid is to be dispensed, it flows through the central port and then through the branch ports causing the sleeve to expand and permitting the fluid to flow out around one end of the sleeve. During such flow, it is possible for contaminants to flow into the expanded end of the sleeve and then through the branch ports and central port, back into the container. An effective blockage of contaminant back flow into the container is not available.
Kulle in U.S. Pat. No. 4,346,704 discloses another valve incorporating an elastic tube or sleeve. A solution is dispensed through a central tube or channel to branch ports, which deliver the fluid to the inside surface of an elastic sleeve or tube. When the fluid is pressurized, it displaces the elastic tube outwardly permitting flow from the branch ports outwardly from the end of the sleeve. The Kulle device is primarily intended for a one-time use, such as in dispensing an anesthetic. There is no particular problem with a return flow of contaminants into a container or leakage of contents from the container because of such one-time use. The Kulle device is intended to deliver anesthetics at high flow rates and low pressures so that accurate dispensing is possible.
However, such conventional valves lack mechanisms for repeatably locking a seal to a container of sterile fluid so that once opened, the container does not need to be refrigerated nor are preservatives required to safeguard the integrity and concentration of the fluid. The majority of compression-type seal applications are static in nature, providing an effective seal only until the container is first opened. This means the components of the seal do not interact to reseal the container against external matter. Once the user opens a container of fluid, the integrity of the fluid degrades and has a limited use life. In addition, there is currently no mechanism for providing a reusable, locking seal for a container of fluid such that the seal is invariantly secure against vibration as well as against changes in temperature and pressure during long term storage and reuse.
Newton et al., U.S. Pat. No. 5,226,568, purports to disclose a resealable valve and cap for preventing backflow of air into a deformable container. However, unintentional compression of the container by dropping or squeezing, or variation in temperature and pressure may enable excursion of fluid to reside between the seal and cap. In addition, this system is not able to compensate for over-pressure of the cap or friction and abrasion applied by the cap against the seal, which ultimately degrades the seal and may open the contents of the deformable container to contamination.
Therefore, what is needed is a closure that provides a repeatable locking seal for a container of fluid, is shockproof, leakproof, contamination proof and evaporation proof; one that is immune to changes in pressure and temperature and is able to maintain the integrity of the fluid by preventing the unwanted passage of matter in either direction between uses. Such a seal would extend the use life of a product essentially to the limit of its shelf life.
The shelf life defined herein is the length of time an unopened product, such as a packaged food, a chemical preparation, or a pharmaceutical product, may be stored without deteriorating and remain effective for use. The use life or useful-life is the length of time after opening the container or package, i.e., its first use, that a product may be used, without deteriorating and remain effective for use. Most fluids are sensitive to contact with the environment and degrade due to hydrolysis, oxidation and microbial attack. In most cases, the use life is considerably shorter than the shelf life. Therefore, what is needed is a container closure that extends a fluid""s use life up to its shelf life, a closure that behaves throughout multiple deliveries as if its associated container had never been opened.
An aspect of the present invention provides a modular valve assembly for effecting a sealing engagement with the neck of a flexible container enabling the easy dispensing of fluid while preventing any leakage, evaporation, or back flow of contaminants, including air and microbes, through the valve assembly into the container holding the remaining fluid. Thermostable fluids delivered through this assembly have no need for preservatives nor require refrigeration. Another aspect of the invention provides a valve assembly that seals to the interior and exterior surfaces of a container over a wide range of tolerances without concern for the presence of flash or other nonconformities on the neck of the container.
An aspect of the invention effects a primary seal on top of a neck of a flexible container. It also effects a secondary seal on the interior surface of the container and a locking seal on the exterior surface or threads of the neck of the flexible container. The flexible container can be a squeeze bottle, a plastic tube, a syringe or piston, a pouch, or a bag. The container also may be a combination two or more of these. For example, the container having flexible walls can enclose a plastic bag wherein the bag attaches to the neck of a container or any other containment vessel. Such vessel is characterized by a compressible or volumetrically reducible reservoir so that flexible walls for applying a pressure will expel or cause a fluid to flow.
The valve assembly comprises a seat in cooperative engagement with a seal, a segmented retainer and a threaded or snap cap. As the cap is seated, the retainer segments close and transmit lateral compressive forces from the closure of the cap to all sealing surfaces of the seal. The geometry of the seat, seal, retainer and cap interact to ensure that residual fluid is forced progressively outward into a recess between the cap and the tip region of the seat. When the cap is in the seated or closed position, the compressive forces provided by the cap against the retainer, seal and seat, respectively provide a shockproof seal of the fluid, which is effective against the ingress or egress of matter at a molecular level, to include even air or volatile solvents. The extent of the seal is such that the valve assembly is immune to variations of pressure and temperature and the container can be accidentally squeezed, dropped or subjected to severe vibration without loss of fluid integrity.
In accordance with an aspect of the present invention, a valve assembly includes an elongated, tapered seat with an elastomeric seal laterally enclosing the outside surface of the seat. The seat defines a fluid flow path through an exit port or orifice located in the side of an upper tapered portion. Pressing the walls of the flexible container activates fluid flow. Fluid passes through the seat through the exit port and into the space between the outside surface of the seat and the elastomeric seal. The seal and seat are configured to create a progressive seal in a reverse direction for the excursion of fluid to prevent fluid from reentering the container. The cooperative engagement of the cap, retainer, seal and seat respectively provide a shockproof sealing closure when the cap is in the seated position.
Another aspect of the invention provides a container neck closure that can be manufactured easily using existing blow molding, injection molding and other molding processes. The components, seat, seal, retainer and cap, are molded separately, assembled, and snap together. These components can be designed to fit conformably over the neck of a container to form a dispensing and delivery system. While the seal functions with precise tolerances and can effect a substantially complete seal of the fluid in the container, the assembly includes a base having an interior and exterior seal for engaging the inner and outer diameter of a container neck. Thus, the assembly can be adapted for variations in tolerances associated with blow molding and high volume production of containers.
The seat is tapered over most of its length, which makes it simple to assemble with the associated seal and retainer. Only about 0.050 cm of seal length is needed to create a reliable barrier. Thus, only a short cylindrical section of the seat is needed to mate conformably against the seal to form an effective barrier. The seal below the exit port is significantly thicker than the portion of the seal above the exit port. This causes any displaced fluids, after closure, to move only toward the aperture at the tip of the seat.
A compressive load provided by the retainer holds down both seal and seat. The retainer has a plurality of segments, typically four to six, outboard of the seal. These segments are displaced inwards toward the seal when a user closes the cap. The tips of the segments further progressively compress the seal above the exit port, preventing backflow. Securing the cap to the retainer compresses the segments of the retainer firmly locking the seal against the seat. This action prevents evaporation or the accidental dispensing of fluid. Alternatively, it is possible to have only a single segment or arm that compresses the exit port area only and thus creates an effective seal.